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If a MachineBasicBlock has multiple ways of reaching another block,

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allow it to have multiple CFG edges to that block. This is needed
to allow MachineBasicBlock::isOnlyReachableByFallthrough to work
correctly. This fixes PR4126.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71018 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-05-05 21:10:19 +00:00
parent 8c87ae229c
commit 5412d06e9c
3 changed files with 28 additions and 9 deletions
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8
lib/CodeGen/IfConversion.cpp
View File

@ -1174,8 +1174,7 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
// Fallthrough edge can't be transferred.
if (Succ == FallThrough)
continue;
if (!ToBBI.BB->isSuccessor(Succ))
ToBBI.BB->addSuccessor(Succ);
ToBBI.BB->addSuccessor(Succ);
}
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
@ -1215,12 +1214,11 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
if (Succ == FallThrough)
continue;
FromBBI.BB->removeSuccessor(Succ);
if (!ToBBI.BB->isSuccessor(Succ))
ToBBI.BB->addSuccessor(Succ);
ToBBI.BB->addSuccessor(Succ);
}
// Now FromBBI always fall through to the next block!
if (NBB && !FromBBI.BB->isSuccessor(NBB))
if (NBB)
FromBBI.BB->addSuccessor(NBB);
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),

6
lib/CodeGen/MachineBasicBlock.cpp
View File

@ -305,11 +305,9 @@ void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
I->getOperand(i).setMBB(New);
}
// Update the successor information. If New was already a successor, just
// remove the link to Old instead of creating another one. PR 1444.
// Update the successor information.
removeSuccessor(Old);
if (!isSuccessor(New))
addSuccessor(New);
addSuccessor(New);
}
/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the

23
test/CodeGen/X86/omit-label.ll Normal file
View File

@ -0,0 +1,23 @@
; RUN: llvm-as < %s | llc -march=x86-64 | grep BB1_1:
; PR4126
; Don't omit this label's definition.
define void @bux(i32 %p_53) nounwind optsize {
entry:
%0 = icmp eq i32 %p_53, 0 ; <i1> [#uses=1]
%1 = icmp sgt i32 %p_53, 0 ; <i1> [#uses=1]
%or.cond = and i1 %0, %1 ; <i1> [#uses=1]
br i1 %or.cond, label %bb.i, label %bb3
bb.i: ; preds = %entry
%2 = add i32 %p_53, 1 ; <i32> [#uses=1]
%3 = icmp slt i32 %2, 0 ; <i1> [#uses=0]
br label %bb3
bb3: ; preds = %bb.i, %entry
%4 = tail call i32 (...)* @baz(i32 0) nounwind ; <i32> [#uses=0]
ret void
}
declare i32 @baz(...)